Major Glitches

There are three Glitches (the first two are only available in the Red, Blue and Yellow versions; the third one is available in the Gold/Silver and Emerald versions, and the Hall of Fame one is very minor) that do not necessarily always create glitched Pokémon, but are themselves glitches that cause events that would not normally happen in the gameplay.

Red/Blue/Yellow:

Glitch City: a mess of pixels that changes depending on where the player is[1]

Mew glitch: allowing players to capture any Pokémon (most especially Mew) without modification, and allowing players to catch most of the glitched Pokémon listed below[2]

Hall of Fame Glitch: When Missingno. has been seen on the save file, the player's Hall Of Fame is badly corrupted with entirely different Pokémon (players can even see Mew in the Hall Of Fame, whether they've seen Mew or not) and very glitched characters and names.

Pokémon Cloning: Variations of the Pokémon cloning trick exist in each Generation of the Pokémon games, each slightly different from one another. The most reliable verison is in Generation III. This Pokémon Cloning version allows players in the Gold/Silver versions to safely clone Pokémon, assuming they have at least somewhat decent timing.[3]

Minor Glitches

Man on roof of Cinnabar Gym: If one does not have the key to the Cinnabar Gym, and surfs on the east coast and returns to land directly infront of the gym, a man will appear on the roof of the gym.

Prevented progress: If one evolves their starter Pokémon before they obtain their Pokédex from Prof. Oak, the game will assume that, since they have 2 Pokémon registered, that they already have a Pokédex, and will not allow them to proceed.

Gold/Silver:

Glitch dimension: Turns everything into strange, random colors and slows the ability to see the party screen and changes the "Poké" in Pokégear to random symbols

Dratini Glitch: After the player speaks to the Dratini in Blackthorn City and uses the Coin Case, the Coin Case's display will change what the coin case says from "Coins: ..." to "Which move?he pp of" permanently unless the game is turned off.

A glitch Pokémon is a Pokémon that exists in a game due to a programming or level design oversight or for beta testing, and as it was not intentionally placed inside the game by Nintendo or Game Freak, it might be hazardous to saved data. They were originally supposed to be place-holders for unused Hex-adresses in the game. Glitch Pokémon are to be avoided due to the risks they may pose to a player's save file.

The following glitched Pokémon can be found in the Gold/Silver versions, but require Gameshark to complete them. (Note: after capturing these Pokémon, the game's graphics have been known to screw up, and the player will find themselves in a Glitch City-like area.)[6][7]

Glitch attacks

A glitch attack, or glitch move, is much like a regular attack except the results are often undesirable. These attacks are often known to be called TM attacks (TM01-TM55 and HM01 to HM05), and are also known to have glitch types (COOLTRAINER-type or 999-type)[citation needed]

Like a glitch Pokémon, glitch attacks were not programmed into the game on purpose and many have been proven to cause damage to game cartridges.

There are ways to teach glitch attacks to certain Pokémon without usage of a cheat-code device such as Gameshark, however, most of the time only glitch Pokémon will learn glitch attacks.[citation needed]

The only widely known ones are those for Pokémon Red, Blue and Yellow. The attacks have the same effect on all three versions. [citation needed]

Also, the move Thunderbolt, when used in some Ruby and Sapphire cartridges, may cause the game to freeze.

Glitch types

There are many different glitch types that are found to be the types of several glitched Pokémon. The most well known are:

Glitch areas

Aside from Glitch City in Generation I, there are several other areas which can only be reached by way of a glitch in the games. Examples of this are areas in the Sevii Islands that are retrievable via their index number pointer, however, do not have any other data.

Pokémon Colosseum glitches

Infinite Ball Glitch

When in a battle with a Shadow Pokémon, have the first Pokémon that is selected use any type of Poké Ball. With the second Pokémon, go back to the items screen and switch the Poké Ball used with another in the pocket using the Y button. After exiting the menu, proceed normally, and when Wes uses the Ball, the number in the bag will not go down.

Pokémon XD glitches

Attack Glitch

In a double battle, if a Pokémon grows to a level at which it can learn a new attack after selecting an attack but before actually attacking, and the attack that was selected is deleted to make room for the new attack, the new attack will be used instead of the one that was selected.

Notes

The Yellow version Missingno. is different from the Red/Blue Missingno., but share the same name. For the Yellow version Missingno., using a Pokémon in Method #3 of the Mew glitch with a special stat of 31, 32, 61, 62 , 63, 67, 68, or 69 would make it appear([2]). Missingno will revert to level 100 if leveled up to over level 255 with Rare Candies or if it fights in battle and wins.

The Pokémon 3TrainerPoké, Charizard 'M and Q are the only known catchable glitch Pokémon that cannot be directly caught using the Mew glitch.

The glitch known as ".4" can corrupt saved data if it uses a certain glitch move, making it impossible to continue and forcing the player to start a new game.